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Finding the Fourth Proportional to 690.51, 1,040.97 and 643.53

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Solution

The fourth proportional to 690.51, 1,040.97 and 643.53 is: 970.15

Step by Step Solution

  1. Step 1: Write the proportion equation
    690.51 : 1,040.97 = 643.53 : x
  2. Step 2: Convert to fraction form
    690.51/1,040.97 = 643.53/x
  3. Step 3: Cross multiply
    690.51x = 1,040.97 × 643.53
  4. Step 4: Simplify right side
    690.51x = 669,895.42
  5. Step 5: Solve for x
    x = 669,895.42/690.51
  6. Step 6: Final answer
    x = 970.15

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Why These Related Problems?

These problems maintain the same ratio (1.51) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.